The present invention relates generally to medical catheters, such as gastrostomy feeding tubes, and relates more particularly to medical catheter assemblies, such as percutaneous endoscopic gastrostomy (PEG) devices.
Certain patients are unable to take food and/or medications transorally due to an inability to swallow. Such an inability to swallow may be due to a variety of reasons, such as esophageal cancer, neurological impairment and the like. Although the intravenous administration of food and/or medications to such patients may be a viable short-term approach, it is not well-suited for the long-term. Accordingly, the most common approach to the long-term feeding of such patients involves gastrostomy, i.e., the creation of a feeding tract or stoma between the stomach and the upper abdominal wall. Feeding is then typically performed by administering food through a catheter or feeding tube that has been inserted into the feeding tract, with the distal end of the feeding tube extending into the stomach and being retained therein by an internal anchor or bolster and the proximal end of the feeding tube extending through the abdominal wall.
Although gastrostomies were first performed surgically, most gastrostomies are now performed using percutaneous endoscopy and result in the implantation of a catheter/bolster assembly (also commonly referred to as a percutaneous endoscopic gastrostomy (PEG) device) in the patient. Two of the more common techniques for implanting a PEG device in a patient are “the push method” (also known as “the Sacks-Vine method”) and “the pull method” (also known as “the Gauderer-Ponsky method”). Information regarding the foregoing two methods may be found in the following patents, all of which are incorporated herein by reference: U.S. Pat. No. 5,391,159, inventors Hirsch et al., which issued Feb. 21, 1995; U.S. Pat. No. 5,167,627, inventors Clegg et al., which issued Dec. 1, 1992; U.S. Pat. No. 5,112,310, inventor Grobe, which issued May 12, 1992; U.S. Pat. No. 4,900,306, inventors Quinn et al., which issued Feb. 13, 1990; and U.S. Pat. No. 4,861,334, inventor Nawaz, which issued Aug. 29, 1989.
According to the push method, the distal end of an endoscope is inserted into a patient's mouth and is passed through the esophagus into the stomach. After distension of the stomach by inflation, an entry site on the abdomen is identified, and an incision is made by passing a needle with an outer cannula (e.g., a Seldinger needle) through the abdominal wall and into the stomach. The needle is then removed while keeping the cannula in place. Next, a snare is inserted into the stomach via the endoscope and is looped over the distal end of the cannula. A first end of a flexible guidewire is then passed through the cannula and into the stomach where it is grasped by the snare, the second end of the guidewire remaining external to the patient. The endoscope and the snare are then withdrawn from the mouth of the patient to deliver the first end of the guidewire.
A catheter assembly is then inserted over the first end of the guidewire and is pushed over the guidewire towards its second end. The catheter assembly typically comprises a gastrostomy feeding tube, the gastrostomy feeding tube having a dome-shaped internal bolster disposed at its trailing end and having a tubular dilator serially connected to its leading end. The gastrostomy feeding tube and the internal bolster (also referred to collectively as a “PEG device”) are typically made of a soft, biocompatible material, like silicone rubber, and may form a unitary structure. The dilator, which tapers in outer diameter from its trailing end to its leading end, is typically made of polyethylene or a like material which is stiffer than silicone but which still possesses some flexibility. Advancement of the catheter assembly over the guidewire continues until the front end of the dilator reaches the cannula and pushes the cannula out through the abdominal wall of the patient. The front end of the dilator is then pulled through the abdominal wall until the front end of the gastrostomy feeding tube emerges from the abdomen and, thereafter, the internal bolster at the rear end of the gastrostomy feeding tube engages the gastric wall.
With the internal bolster in place against the gastric wall, a proximal portion of the implanted gastrostomy feeding tube is then typically cut and removed from the implanted tube to reduce the externally-extending portion of the tube to a desired length. An external bolster is typically secured to the remaining implanted portion of the feeding tube to engage the abdomen in such a way as to prevent longitudinal movement of the feeding tube within the stoma tract. Additionally, a “Y-port” adapter is typically attached to the proximal end of the implanted feeding tube, the Y-port adapter being adapted to receive a pair of connector tips through which food and/or medications may be dispensed. In addition, a detachable locking clip is typically secured to the implanted feeding tube at a point between the external bolster and the Y-port adapter to prevent gastric fluids from escaping through the proximal end of the feeding tube when the feeding tube is not in use.
As can readily be appreciated, because the leading end of the gastrostomy feeding tube is drawn through the abdomen by pulling on the dilator, the connection between the dilator and the gastrostomy feeding tube must be strong enough to withstand the tensile force applied thereto. Otherwise, the gastrostomy feeding tube may separate from the dilator prior to emergence of the feeding tube from the patient, thereby requiring the feeding tube to be retrieved from the patient and possibly leading to undesired complications. For PEG assembly connections, such as the aforementioned connection between the gastrostomy feeding tube and the dilator, the industry standard minimum tensile strength is 17 pounds (see BS EN 1615:2000).
Historically, however, this standard has not typically been met by the conventional type of connection used to couple a dilator to a gastrostomy feeding tube. An example of such a connection typically comprises an appropriately dimensioned tubular fitting having barbs at opposite ends thereof. One end of the tubular fitting is inserted into the trailing end of the dilator, and the opposite end of the fitting is inserted into the leading end of the gastrostomy feeding tube. The connection also comprises a short length of plastic tubing, which is shrink-wrapped around the trailing end of the dilator and the leading end of the feeding tube (as well as surrounding the fitting disposed within the trailing end of the dilator and the leading end of the feeding tube).
In addition to failing frequently to meet the minimum tensile strength required for a connection between a dilator and a feeding tube, other shortcomings with the above-described connection are (i) that the application of the shrink-wrapped length of tubing to the assembly requires the expenditure of time and labor, (ii) that the shrink-wrapped tubing undesirably increases the cross-sectional profile of the assembly, and (iii) that there is a perception that the ends of the shrink-wrapped tubing, which ends do not lie flush with the dilator or the feeding tube, may snag tissue as the assembly makes its winding path through the patient.
According to the pull method, the distal end of an endoscope is inserted into a patient's mouth and is passed through the esophagus into the stomach. After distension of the stomach by inflation, an entry site on the abdomen is identified, and an incision is made by passing a needle with an outer cannula (e.g., a Seldinger needle) through the abdominal wall and into the stomach. The needle is then removed while keeping the cannula in place. Next, a snare is inserted into the stomach via the endoscope and is looped over the distal end of the cannula. A first end of a suture is then passed through the cannula and into the stomach where it is grasped by the snare, the second end of the suture remaining external to the patient. The endoscope and the snare are then withdrawn from the mouth of the patient to deliver the first end of the suture. The first end of the suture is then coupled to the leading end of a catheter assembly, the catheter assembly comprising a gastrostomy feeding tube having an internal bolster at its trailing end and a plastic fitting at its leading end. The plastic fitting has a barbed rear portion mounted within the leading end of the feeding tube and a conical front portion that serves as a dilator, said conical front portion tapering in diameter from the leading end of the feeding tube to a front tip. A wire loop is fixed to the front tip of the plastic fitting, the first end of the suture being tied to the wire loop.
Using the second end of the suture, the catheter assembly is then pulled retrograde through the patient until the gastrostomy feeding tube emerges from the abdomen of the patient and the internal bolster engages the gastric wall of the patient. Next, as is the case in the push method, the implanted gastrostomy feeding tube is typically cut to a desired length, an external bolster is typically secured to the cut implanted tube, a “Y-port” adapter is typically attached to the proximal end of the implanted feeding tube, and a detachable locking clip is typically secured to the implanted feeding tube at a point between the external bolster and the Y-port adapter.
As can readily be appreciated, because the catheter assembly is moved into position within the patient's body by pulling on the suture, it is very important that the plastic fitting maintain its coupling to the gastrostomy feeding tube.